large refactoring: use FSMs for lchans; add inter-BSC HO

Add FSMs:

- timeslot_fsm: handle dynamic timeslots and OML+RSL availability.
- lchan_fsm: handle an individual lchan activation, RTP stream and release,
  signal the appropriate calling FSMs on success, failure, release.
- mgw_endpoint_fsm: handle one entire endpoint with several CI.
- assignment_fsm: BSSMAP Assignment Request.
- handover_fsm: all of intra, inter-MO and inter-MT handover.

Above FSMs absorb large parts of the gscon FSM. The gscon FSM was surpassing
the maximum amount events (32), and it is more logical to treat assignment,
handover and MGW procedures in separate FSMs.

- Add logging macros for each FSM type:
  - LOG_TS()
  - LOG_LCHAN()
  - LOG_MGWEP(), LOG_CI()
  - LOG_ASSIGNMENT()
  - LOG_HO()
  These log with the osmo_fsm_inst where present.
  New style decision: logging without a final newline char is awkward,
  especially for gsmtap logging and when other logs interleave LOGPC() calls;
  we have various cases where the final \n goes missing, and also this invokes
  the log category checking N times instead of once.
  So I decided to make these macros *always* append a newline, but only if
  there is no final newline yet. I hope that the compiler optimizes the
  strlen() of the constant format strings away. Thus I can log with or without
  typing "\n" and always get an \n termination anyway.

General:

- replace osmo_timers, state enums and program-wide osmo_signal_dispatch()
  with dedicated FSM timeouts, states and events.

- introduce a common way to handle Tnnn timers: gsm_timers.h/.c: struct T_def.
  These can be used (with some macro magic) to define a state's timeout once,
  and not make mistakes for each osmo_fsm_inst_state_chg().

Details:

bsc_subscr_conn_fsm.c:

- move most states of this FSM to lchan_fsm, assignment_fsm, handover_fsm and
  mgw_endpoint_fsm.

- There is exactly one state for an ongoing Assignment, with all details
  handled in conn->assignment.fi. The state relies on the assignment_fsm's
  timeout.

- There is one state for an ongoing Handover; except for an incoming Handover
  from a remote BSS, the gscon remains in ST_INIT until the new lchan and conn
  are both established.

- move bssmap_add_lcls_status() to osmo_bsc_lcls.c

abis_rsl.c:

- move all dynamic timeslot logic away into timeslot_fsm. Only keep plain send/receive functions in
  abis_rsl.c

- reduce some rsl functions to merely send a message, rename to "_tx_".
  - rsl_ipacc_mdcx(): add '_tx_' in the name; move parts that change the lchan state out into the
    lchan_fsm, the lchan->abis_ip.* are now set there prior to invoking this function.

- move all timers and error/release handling away into various FSMs.

- tweak ipa_smod_s_for_lchan() and ipa_rtp_pt_for_lchan() to not require an
  lchan passed, but just mode,type that they require. Rename to
  ipacc_speech_mode*() and ipacc_payload_type().

- add rsl_forward_layer3_info, used for inter-BSC HO MO, to just send the RR
  message received during BSSMAP Handover Command.

- move various logging to LOG_LCHAN() in order to log with the lchan FSM instance.
  One drawback is that the lchan FSM is limited to one logging category, i.e. this moves some logging
  from DRR to DRSL. It might actually make sense to combine those categories.

- lose LOGP...LOGPC logging cascades: they are bad for gsmtap logging and for performance.

- handle_classmark_chg(): change logging, move cm2 len check out of the cm3 condition (I hope that's
  correct).

- gsm48_send_ho_cmd(): split off gsm48_make_ho_cmd() which doesn't send right away, so that during
  inter-bsc HO we can make an RR Handover Command to send via the MSC to the remote BSS.

assignment_fsm.c:

- the Chan Mode Modify in case of re-using the same lchan is not implemented
  yet, because this was also missing in the previous implementation (OS#3357).

osmo_bsc_api.c:

- simplify bsc_mr_config() and move to lchan_fsm.c, the only caller; rename to
  lchan_mr_config(). (bsc_mr_config() used to copy the values to mr_bts_lv
  twice, once by member assignment and then again with a memcpy.)

- During handover, we used to copy the MR config from the old lchan. Since we
  may handover between FR and HR, rather set the MR Config anew every time, so
  that FR rates are always available on FR lchans, and never on HR lchans.

Depends: I03ee7ce840ecfa0b6a33358e7385528aabd4873f (libosmocore),
         I1f2918418c38918c5ac70acaa51a47adfca12b5e (libosmocore)
Change-Id: I82e3f918295daa83274a4cf803f046979f284366

1 files changed, 73 insertions, 223 deletions

diff --git a/src/osmo-bsc/gsm_04_08_rr.c b/src/osmo-bsc/gsm_04_08_rr.c
index e6b654ac1..8950d939a 100644
--- a/src/osmo-bsc/gsm_04_08_rr.c
+++ b/src/osmo-bsc/gsm_04_08_rr.c
@@ -36,14 +36,16 @@
 #include <osmocom/bsc/signal.h>
 #include <osmocom/bsc/bsc_subscr_conn_fsm.h>
 #include <osmocom/bsc/gsm_04_08_rr.h>
-#include <osmocom/bsc/chan_alloc.h>
+#include <osmocom/bsc/lchan_fsm.h>
+#include <osmocom/bsc/assignment_fsm.h>
+#include <osmocom/bsc/handover_fsm.h>
 #include <osmocom/bsc/bsc_api.h>
 
 /* should ip.access BTS use direct RTP streams between each other (1),
  * or should OpenBSC always act as RTP relay/proxy in between (0) ? */
 int ipacc_rtp_direct = 1;
 
-static int gsm48_sendmsg(struct msgb *msg)
+int gsm48_sendmsg(struct msgb *msg)
 {
 	if (msg->lchan)
 		msg->dst = msg->lchan->ts->trx->rsl_link;
@@ -352,15 +354,13 @@ int gsm48_multirate_config(uint8_t *lv, const struct amr_multirate_conf *mr, con
 #define GSM48_HOCMD_CCHDESC_LEN	16
 
 /* Chapter 9.1.15: Handover Command */
-int gsm48_send_ho_cmd(struct gsm_lchan *old_lchan, struct gsm_lchan *new_lchan,
-		      uint8_t power_command, uint8_t ho_ref)
+struct msgb *gsm48_make_ho_cmd(struct gsm_lchan *new_lchan, uint8_t power_command, uint8_t ho_ref)
 {
 	struct msgb *msg = gsm48_msgb_alloc_name("GSM 04.08 HO CMD");
 	struct gsm48_hdr *gh = (struct gsm48_hdr *) msgb_put(msg, sizeof(*gh));
 	struct gsm48_ho_cmd *ho =
 		(struct gsm48_ho_cmd *) msgb_put(msg, sizeof(*ho));
 
-	msg->lchan = old_lchan;
 	gh->proto_discr = GSM48_PDISC_RR;
 	gh->msg_type = GSM48_MT_RR_HANDO_CMD;
 
@@ -395,6 +395,16 @@ int gsm48_send_ho_cmd(struct gsm_lchan *old_lchan, struct gsm_lchan *new_lchan,
 		msgb_tlv_put(msg, GSM48_IE_MUL_RATE_CFG, new_lchan->mr_ms_lv[0],
 			new_lchan->mr_ms_lv + 1);
 
+	return msg;
+}
+
+int gsm48_send_ho_cmd(struct gsm_lchan *old_lchan, struct gsm_lchan *new_lchan,
+		      uint8_t power_command, uint8_t ho_ref)
+{
+	struct msgb *msg = gsm48_make_ho_cmd(new_lchan, power_command, ho_ref);
+	if (!msg)
+		return -EINVAL;
+	msg->lchan = old_lchan;
 	return gsm48_sendmsg(msg);
 }
 
@@ -472,11 +482,14 @@ int gsm48_rx_rr_modif_ack(struct msgb *msg)
 	struct gsm48_chan_mode_modify *mod =
 				(struct gsm48_chan_mode_modify *) gh->data;
 
-	DEBUGP(DRR, "CHANNEL MODE MODIFY ACK\n");
+	LOG_LCHAN(msg->lchan, LOGL_DEBUG, "CHANNEL MODE MODIFY ACK for %s\n",
+		  gsm48_chan_mode_name(mod->mode));
 
 	if (mod->mode != msg->lchan->tch_mode) {
-		LOGP(DRR, LOGL_ERROR, "CHANNEL MODE change failed. Wanted: %d Got: %d\n",
-			msg->lchan->tch_mode, mod->mode);
+		LOG_LCHAN(msg->lchan, LOGL_ERROR,
+			  "CHANNEL MODE MODIFY ACK has wrong mode: Wanted: %s Got: %s\n",
+			  gsm48_chan_mode_name(msg->lchan->tch_mode),
+			  gsm48_chan_mode_name(mod->mode));
 		return -1;
 	}
 
@@ -505,7 +518,7 @@ int gsm48_rx_rr_modif_ack(struct msgb *msg)
 	/* FIXME: we not only need to do this after mode modify, but
 	 * also after channel activation */
 	if (is_ipaccess_bts(msg->lchan->ts->trx->bts) && mod->mode != GSM48_CMODE_SIGN)
-		rsl_ipacc_crcx(msg->lchan);
+		rsl_tx_ipacc_crcx(msg->lchan);
 	return rc;
 }
 
@@ -589,41 +602,6 @@ int gsm48_parse_meas_rep(struct gsm_meas_rep *rep, struct msgb *msg)
 	return 0;
 }
 
-/* 9.2.5 CM service accept */
-int gsm48_tx_mm_serv_ack(struct gsm_subscriber_connection *conn)
-{
-	struct msgb *msg = gsm48_msgb_alloc_name("GSM 04.08 SERV ACK");
-	struct gsm48_hdr *gh = (struct gsm48_hdr *) msgb_put(msg, sizeof(*gh));
-
-	msg->lchan = conn->lchan;
-
-	gh->proto_discr = GSM48_PDISC_MM;
-	gh->msg_type = GSM48_MT_MM_CM_SERV_ACC;
-
-	DEBUGP(DMM, "-> CM SERVICE ACK\n");
-
-	gscon_submit_rsl_dtap(conn, msg, 0, 0);
-	return 0;
-}
-
-/* 9.2.6 CM service reject */
-int gsm48_tx_mm_serv_rej(struct gsm_subscriber_connection *conn,
-				enum gsm48_reject_value value)
-{
-	struct msgb *msg;
-
-	msg = gsm48_create_mm_serv_rej(value);
-	if (!msg) {
-		LOGP(DMM, LOGL_ERROR, "Failed to allocate CM Service Reject.\n");
-		return -1;
-	}
-
-	DEBUGP(DMM, "-> CM SERVICE Reject cause: %d\n", value);
-
-	gscon_submit_rsl_dtap(conn, msg, 0, 0);
-	return 0;
-}
-
 /* 9.1.29 RR Status */
 struct msgb *gsm48_create_rr_status(uint8_t cause)
 {
@@ -719,108 +697,6 @@ uint64_t str_to_imsi(const char *imsi_str)
 	return ret;
 }
 
-static void handle_ass_compl(struct gsm_subscriber_connection *conn,
-			     struct msgb *msg)
-{
-	struct gsm48_hdr *gh = msgb_l3(msg);
-	enum gsm48_rr_cause cause;
-
-	/* Expecting gsm48_hdr + cause value */
-	if (msgb_l3len(msg) != sizeof(*gh) + 1) {
-		LOGPLCHAN(msg->lchan, DRR, LOGL_ERROR,
-			  "RR Assignment Complete: length invalid: %u, expected %zu\n",
-			  msgb_l3len(msg), sizeof(*gh) + 1);
-		return;
-	}
-
-	cause = gh->data[0];
-
-	LOGPLCHAN(msg->lchan, DRR, LOGL_DEBUG, "ASSIGNMENT COMPLETE cause = %s\n",
-		  rr_cause_name(cause));
-
-	if (conn->ho) {
-		struct lchan_signal_data sig = {
-			.lchan = msg->lchan,
-		};
-		osmo_signal_dispatch(SS_LCHAN, S_LCHAN_ASSIGNMENT_COMPL, &sig);
-		/* FIXME: release old channel */
-
-		/* send pending messages, if any */
-		gscon_dtap_queue_flush(conn, 1);
-
-		return;
-	}
-
-	if (conn->secondary_lchan != msg->lchan) {
-		LOGPLCHAN(msg->lchan, DRR, LOGL_ERROR,
-			  "RR Assignment Complete does not match conn's secondary lchan.\n");
-		return;
-	}
-
-	lchan_release(conn->lchan, 0, RSL_REL_LOCAL_END);
-	conn->lchan = conn->secondary_lchan;
-	conn->secondary_lchan = NULL;
-
-	/* send pending messages, if any */
-	gscon_dtap_queue_flush(conn, 1);
-
-	if (is_ipaccess_bts(conn_get_bts(conn)) && conn->lchan->tch_mode != GSM48_CMODE_SIGN)
-		rsl_ipacc_crcx(conn->lchan);
-
-	bsc_assign_compl(conn, cause);
-}
-
-static void handle_ass_fail(struct gsm_subscriber_connection *conn,
-			    struct msgb *msg)
-{
-	uint8_t *rr_failure;
-	struct gsm48_hdr *gh;
-
-	if (conn->ho) {
-		struct lchan_signal_data sig;
-		struct gsm48_hdr *gh = msgb_l3(msg);
-
-		LOGPLCHAN(msg->lchan, DRR, LOGL_DEBUG, "ASSIGNMENT FAILED cause = %s\n",
-			  rr_cause_name(gh->data[0]));
-
-		sig.lchan = msg->lchan;
-		sig.mr = NULL;
-		osmo_signal_dispatch(SS_LCHAN, S_LCHAN_ASSIGNMENT_FAIL, &sig);
-		/* FIXME: release allocated new channel */
-
-		/* send pending messages, if any */
-		gscon_dtap_queue_flush(conn, 1);
-
-		return;
-	}
-
-	if (conn->lchan != msg->lchan) {
-		LOGPLCHAN(msg->lchan, DMSC, LOGL_ERROR,
-			  "Assignment failure should occur on primary lchan.\n");
-		return;
-	}
-
-	/* stop the timer and release it */
-	if (conn->secondary_lchan) {
-		lchan_release(conn->secondary_lchan, 0, RSL_REL_LOCAL_END);
-		conn->secondary_lchan = NULL;
-	}
-
-	/* send pending messages, if any */
-	gscon_dtap_queue_flush(conn, 1);
-
-	gh = msgb_l3(msg);
-	if (msgb_l3len(msg) - sizeof(*gh) != 1) {
-		LOGPLCHAN(conn->lchan, DMSC, LOGL_ERROR, "assignment failure unhandled: %zu\n",
-			  msgb_l3len(msg) - sizeof(*gh));
-		rr_failure = NULL;
-	} else {
-		rr_failure = &gh->data[0];
-	}
-
-	bsc_assign_fail(conn, GSM0808_CAUSE_RADIO_INTERFACE_MESSAGE_FAILURE, rr_failure);
-}
-
 static void handle_classmark_chg(struct gsm_subscriber_connection *conn,
 				 struct msgb *msg)
 {
@@ -829,73 +705,35 @@ static void handle_classmark_chg(struct gsm_subscriber_connection *conn,
 	uint8_t cm2_len, cm3_len = 0;
 	uint8_t *cm2, *cm3 = NULL;
 
-	LOGPLCHAN(msg->lchan, DRR, LOGL_DEBUG, "CLASSMARK CHANGE ");
 
 	/* classmark 2 */
 	cm2_len = gh->data[0];
 	cm2 = &gh->data[1];
-	DEBUGPC(DRR, "CM2(len=%u) ", cm2_len);
+
+	if (cm2_len > 3) {
+		LOG_LCHAN(msg->lchan, LOGL_ERROR, "CLASSMARK CHANGE: CM2 too long: %u\n", cm2_len);
+		return;
+	}
 
 	if (payload_len > cm2_len + 1) {
 		/* we must have a classmark3 */
 		if (gh->data[cm2_len+1] != 0x20) {
-			DEBUGPC(DRR, "ERR CM3 TAG\n");
-			return;
-		}
-		if (cm2_len > 3) {
-			DEBUGPC(DRR, "CM2 too long!\n");
+			LOG_LCHAN(msg->lchan, LOGL_ERROR, "CLASSMARK CHANGE: invalid CM3 TAG\n");
 			return;
 		}
 
 		cm3_len = gh->data[cm2_len+2];
 		cm3 = &gh->data[cm2_len+3];
 		if (cm3_len > 14) {
-			DEBUGPC(DRR, "CM3 len %u too long!\n", cm3_len);
+			LOG_LCHAN(msg->lchan, LOGL_ERROR, "CLASSMARK CHANGE: CM3 too long: %u\n",
+				  cm3_len);
 			return;
 		}
-		DEBUGPC(DRR, "CM3(len=%u)\n", cm3_len);
 	}
-	bsc_cm_update(conn, cm2, cm2_len, cm3, cm3_len);
-}
-
-/* Chapter 9.1.16 Handover complete */
-static void handle_rr_ho_compl(struct msgb *msg)
-{
-	struct lchan_signal_data sig;
-	struct gsm48_hdr *gh = msgb_l3(msg);
-
-	LOGPLCHAN(msg->lchan, DRR, LOGL_DEBUG,
-		  "HANDOVER COMPLETE cause = %s\n", rr_cause_name(gh->data[0]));
-
-	sig.lchan = msg->lchan;
-	sig.mr = NULL;
-	osmo_signal_dispatch(SS_LCHAN, S_LCHAN_HANDOVER_COMPL, &sig);
-	/* FIXME: release old channel */
-
-	/* send pending messages, if any */
-	gscon_dtap_queue_flush(msg->lchan->conn, 1);
-}
-
-/* Chapter 9.1.17 Handover Failure */
-static void handle_rr_ho_fail(struct msgb *msg)
-{
-	struct lchan_signal_data sig;
-	struct gsm48_hdr *gh = msgb_l3(msg);
-
-	/* Log on both RR and HO categories: it is an RR message, but is still quite important when
-	 * filtering on HO. */
-	LOGPLCHAN(msg->lchan, DRR, LOGL_DEBUG,
-		  "HANDOVER FAILED cause = %s\n", rr_cause_name(gh->data[0]));
-	LOGPLCHAN(msg->lchan, DHO, LOGL_DEBUG,
-		  "HANDOVER FAILED cause = %s\n", rr_cause_name(gh->data[0]));
-
-	sig.lchan = msg->lchan;
-	sig.mr = NULL;
-	osmo_signal_dispatch(SS_LCHAN, S_LCHAN_HANDOVER_FAIL, &sig);
-	/* FIXME: release allocated new channel */
 
-	/* send pending messages, if any */
-	gscon_dtap_queue_flush(msg->lchan->conn, 1);
+	LOG_LCHAN(msg->lchan, LOGL_DEBUG, "CLASSMARK CHANGE CM2(len=%u) CM3(len=%u)\n",
+		  cm2_len, cm3_len);
+	bsc_cm_update(conn, cm2, cm2_len, cm3, cm3_len);
 }
 
 static void dispatch_dtap(struct gsm_subscriber_connection *conn,
@@ -907,8 +745,8 @@ static void dispatch_dtap(struct gsm_subscriber_connection *conn,
 	int rc;
 
 	if (msgb_l3len(msg) < sizeof(*gh)) {
-		LOGP(DMSC, LOGL_ERROR, "(%s) Message too short for a GSM48 header.\n",
-		     bsc_subscr_name(conn->bsub));
+		LOG_LCHAN(msg->lchan, LOGL_ERROR,
+			  "Message too short for a GSM48 header (%u)\n", msgb_l3len(msg));
 		return;
 	}
 
@@ -924,45 +762,63 @@ static void dispatch_dtap(struct gsm_subscriber_connection *conn,
 	 * will call api->compl_l3() for it */
 	switch (pdisc) {
 	case GSM48_PDISC_RR:
+		LOG_LCHAN(msg->lchan, LOGL_DEBUG, "Rx %s\n", gsm48_rr_msg_name(msg_type));
 		switch (msg_type) {
 		case GSM48_MT_RR_GPRS_SUSP_REQ:
-			LOGPLCHAN(msg->lchan, DRR, LOGL_DEBUG,
-				  "%s\n", gsm48_rr_msg_name(GSM48_MT_RR_GPRS_SUSP_REQ));
+			/* do something? */
 			break;
 		case GSM48_MT_RR_STATUS:
-			LOGPLCHAN(msg->lchan, DRR, LOGL_NOTICE,
-				  "%s (cause: %s)\n", gsm48_rr_msg_name(GSM48_MT_RR_STATUS),
-				  rr_cause_name(gh->data[0]));
+			LOG_LCHAN(msg->lchan, LOGL_NOTICE, "RR Status: %s\n", rr_cause_name(gh->data[0]));
+			/* do something? */
 			break;
 		case GSM48_MT_RR_MEAS_REP:
 			/* This shouldn't actually end up here, as RSL treats
 			* L3 Info of 08.58 MEASUREMENT REPORT different by calling
 			* directly into gsm48_parse_meas_rep */
-			LOGPLCHAN(msg->lchan, DMEAS, LOGL_ERROR,
-				  "DIRECT GSM48 MEASUREMENT REPORT ?!?\n");
+			LOG_LCHAN(msg->lchan, LOGL_ERROR, "DIRECT GSM48 MEASUREMENT REPORT ?!?\n");
 			gsm48_tx_rr_status(conn, GSM48_RR_CAUSE_MSG_TYPE_N_COMPAT);
 			break;
 		case GSM48_MT_RR_HANDO_COMPL:
-			handle_rr_ho_compl(msg);
+			/* Chapter 9.1.16 Handover complete */
+			if (!conn->ho.fi)
+				LOG_LCHAN(msg->lchan, LOGL_ERROR,
+					  "Rx RR Handover Complete, but no handover is ongoing\n");
+			else
+				osmo_fsm_inst_dispatch(conn->ho.fi, HO_EV_RR_HO_COMPLETE, msg);
 			break;
 		case GSM48_MT_RR_HANDO_FAIL:
-			handle_rr_ho_fail(msg);
+			/* Chapter 9.1.17 Handover Failure */
+			if (!conn->ho.fi)
+				LOG_LCHAN(msg->lchan, LOGL_ERROR,
+					  "Rx RR Handover Fail, but no handover is ongoing\n");
+			else
+				osmo_fsm_inst_dispatch(conn->ho.fi, HO_EV_RR_HO_FAIL, msg);
 			break;
 		case GSM48_MT_RR_CIPH_M_COMPL:
 			bsc_cipher_mode_compl(conn, msg, conn->lchan->encr.alg_id);
 			break;
 		case GSM48_MT_RR_ASS_COMPL:
-			handle_ass_compl(conn, msg);
+			if (conn->assignment.fi)
+				osmo_fsm_inst_dispatch(conn->assignment.fi,
+						       ASSIGNMENT_EV_RR_ASSIGNMENT_COMPLETE, msg);
+			else
+				LOGPLCHAN(msg->lchan, DRR, LOGL_ERROR,
+					  "Rx RR Assignment Complete, but no assignment is ongoing\n");
 			break;
 		case GSM48_MT_RR_ASS_FAIL:
-			handle_ass_fail(conn, msg);
+			if (conn->assignment.fi)
+				osmo_fsm_inst_dispatch(conn->assignment.fi,
+						       ASSIGNMENT_EV_RR_ASSIGNMENT_FAIL, msg);
+			else
+				LOGPLCHAN(msg->lchan, DRR, LOGL_ERROR,
+					  "Rx RR Assignment Failure, but no assignment is ongoing\n");
 			break;
 		case GSM48_MT_RR_CHAN_MODE_MODIF_ACK:
 			rc = gsm48_rx_rr_modif_ack(msg);
 			if (rc < 0)
-				bsc_assign_fail(conn, GSM0808_CAUSE_NO_RADIO_RESOURCE_AVAILABLE, NULL);
+				osmo_fsm_inst_dispatch(msg->lchan->fi, LCHAN_EV_CHAN_MODE_MODIF_ERROR, &rc);
 			else
-				bsc_assign_compl(conn, 0);
+				osmo_fsm_inst_dispatch(msg->lchan->fi, LCHAN_EV_CHAN_MODE_MODIF_ACK, msg);
 			break;
 		case GSM48_MT_RR_CLSM_CHG:
 			handle_classmark_chg(conn, msg);
@@ -974,8 +830,8 @@ static void dispatch_dtap(struct gsm_subscriber_connection *conn,
 			break;
 		default:
 			/* Drop unknown RR message */
-			LOGPLCHAN(msg->lchan, DRR, LOGL_NOTICE,
-				  "Dropping %s 04.08 RR message\n", gsm48_rr_msg_name(msg_type));
+			LOG_LCHAN(msg->lchan, LOGL_NOTICE, "Unknown RR message: %s\n",
+				  gsm48_rr_msg_name(msg_type));
 			gsm48_tx_rr_status(conn, GSM48_RR_CAUSE_MSG_TYPE_N);
 			break;
 		}
@@ -989,36 +845,30 @@ static void dispatch_dtap(struct gsm_subscriber_connection *conn,
 /*! \brief RSL has received a DATA INDICATION with L3 from MS */
 int gsm0408_rcvmsg(struct msgb *msg, uint8_t link_id)
 {
-	int rc;
 	struct gsm_lchan *lchan;
 
 	lchan = msg->lchan;
-	if (lchan->state != LCHAN_S_ACTIVE) {
-		LOGPLCHAN(msg->lchan, DRSL, LOGL_INFO, "Got data in non active state, discarding.\n");
+	if (!lchan_may_receive_data(lchan)) {
+		LOG_LCHAN(msg->lchan, LOGL_INFO, "Got data in non active state, discarding.\n");
 		return -1;
 	}
 
-
 	if (lchan->conn) {
 		/* if we already have a connection, forward via DTAP to
 		 * MSC */
 		dispatch_dtap(lchan->conn, link_id, msg);
 	} else {
 		/* allocate a new connection */
-		rc = BSC_API_CONN_POL_REJECT;
 		lchan->conn = bsc_subscr_con_allocate(msg->lchan->ts->trx->bts->network);
 		if (!lchan->conn) {
-			lchan_release(lchan, 1, RSL_REL_NORMAL);
+			lchan_release(lchan, false, true, RSL_ERR_EQUIPMENT_FAIL);
 			return -1;
 		}
 		lchan->conn->lchan = lchan;
 
 		/* fwd via bsc_api to send COMPLETE L3 INFO to MSC */
-		rc = bsc_compl_l3(lchan->conn, msg, 0);
-
-		if (rc != BSC_API_CONN_POL_ACCEPT) {
-			//osmo_fsm_inst_dispatch(lchan->conn->fi, FIXME, NULL);
-		}
+		bsc_compl_l3(lchan->conn, msg, 0);
+		/* conn shall release lchan on teardown, also if this Layer 3 Complete is rejected. */
 	}
 
 	return 0;